Alpha channels transparency turns black with multiple billboards in front of one another.
I tried editing the advanced material properties opacity modes and tried this in conjunction with the textures opacity mode, but nothing worked.
I instanced the geo and had the billboards look at the origin. I want to simulate brush, forests, grass, etc
I looks like it happens 3-4 render layers deep.
I have a temporary solution if I render in passes.
have you tried to crank up the Ray bounces in the Setting/advanced tab? by default is 6 , try like 12 and then up...see if that works